I was the original poster and I think the thread has gotten off track. Maybe my original post was not clear enough. I know what the manufacturer recommends, multi viscosity engine oil. Somwhere in the PO's documents was a comment about using Rotella Synthetic in the transmissions and I was wondering if there is an easy way to determine if the oil in the transmissions is synthetic or not.

Sure takes me a lot longer to hunt and peck "transmission".

Bob

I don't know of an easy way to tell whether it is synthetic or not, but if the mgr says multi grade, I'd just drain what's there and replace it with T6. Just curious, but do you have a transmission oil cooler?

__________________Delfin
"Dad always thought laughter was the best medicine, which I guess is why several of us died of tuberculosis." - Jack Handy